Production of carbon-containing pyrite spherules induced by hyperthermophilic Thermococcales: a biosignature? - Sorbonne Université
Journal Articles (Data Paper) Frontiers in Microbiology Year : 2023

Production of carbon-containing pyrite spherules induced by hyperthermophilic Thermococcales: a biosignature?

Abstract

Thermococcales, a major order of hyperthermophilic archaea inhabiting iron- and sulfur-rich anaerobic parts of hydrothermal deep-sea vents, are known to induce the formation of iron phosphates, greigite (Fe 3 S 4 ) and abundant quantities of pyrite (FeS 2 ), including pyrite spherules. In the present study, we report the characterization of the sulfide and phosphate minerals produced in the presence of Thermococcales using X-ray diffraction, synchrotron-based X ray absorption spectroscopy and scanning and transmission electron microscopies. Mixed valence Fe(II)-Fe(III) phosphates are interpreted as resulting from the activity of Thermococcales controlling phosphorus–iron–sulfur dynamics. The pyrite spherules (absent in abiotic control) consist of an assemblage of ultra-small nanocrystals of a few ten nanometers in size, showing coherently diffracting domain sizes of few nanometers. The production of these spherules occurs via a sulfur redox swing from S 0 to S –2 and then to S –1 , involving a comproportionation of (-II) and (0) oxidation states of sulfur, as supported by S-XANES data. Importantly, these pyrite spherules sequester biogenic organic compounds in small but detectable quantities, possibly making them good biosignatures to be searched for in extreme environments.
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hal-04202920 , version 1 (11-09-2023)

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Chloé Truong, Sylvain Bernard, Guillaume Morin, Pierre Le Pape, Camille Baya, et al.. Production of carbon-containing pyrite spherules induced by hyperthermophilic Thermococcales: a biosignature?. Frontiers in Microbiology, 2023, 14, ⟨10.3389/fmicb.2023.1145781⟩. ⟨hal-04202920⟩
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